The kinetic-theory assumptions, P = ⅓ρc̄² and what it proves, the three molecular speeds and their ratio, energy as (3/2)k_BT per molecule, degrees of freedom, and C_p − C_v = R.
Unit 2 carries 7 of the 50 physics marks; with six chapters sharing them, this one averages a little over one (MEC publishes weights by unit, not by chapter). It is the hinge of the whole unit: the two formulae derived here, P = ⅓ρc̄² and ½mc̄² = (3/2)k_BT, are what turn "hot" into mechanics, and everything in the next two chapters — the four processes, C_p − C_v = R, the efficiency of an engine — stands on them.
The MEC scope lines are: Molecular properties of an ideal gas; Pressure, volume, temperature, rms speed and energy. The headings below are those two points, in MEC's order.
Three ways it is asked: recall (the assumptions of kinetic theory, the value of R, γ for a monatomic gas, the order of the three speeds); understanding (why the internal energy of an ideal gas depends on temperature alone, why C_p must exceed C_v, what happens to the Maxwell curve when the gas is heated or the molecule made heavier); application (an rms speed from T and M, a pressure after a temperature change, the temperature at which hydrogen matches oxygen, γ from a measured C_p).
Upgrade to unlock this and every premium study note, formula sheet and high-yield summary — plus unlimited mocks and full solutions.
See the plansHeat, Temperature and Thermometers: What Each One Can Read
Heat against temperature against internal energy, the scales and the −40 coincidence, the zeroth law, conduction, convection and radiation, and the three thermometers MEC names side by side.
Heat and Thermodynamics: Unit Map and Reading Order
What the Heat and thermodynamics unit covers, how many of the 50 Physics questions it carries, and the order to read its six chapter notes in.
Thermal Expansion: One Coefficient, Three Dimensions
Why α : β : γ is 1 : 2 : 3, how a hole and a bimetallic strip behave, why a pendulum clock loses time in summer, and the real-against-apparent expansion of a liquid in its vessel.
Quantity of Heat: Mixtures, Latent Heat and the Triple Point
Heat capacity against specific heat capacity, the method of mixtures done cleanly, latent heats and the heating curve read properly, evaporation against boiling, and the triple point of water.